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2024-10-12 17:19:46 +08:00
# CustomFieldNotify
- **功能描述:** 阻止UHT为该类生成FieldNotify的相关代码。
- **引擎模块:** UHT
- **元数据类型:** bool
- **作用机制:** 在ClassFlags中增加[HasCustomFieldNotify](../../../Flags/EClassFlags/HasCustomFieldNotify.md)
- **常用程度:** 0
阻止UHT为该类生成FieldNotify的相关代码。
在源码里只在UWidget上使用例如该类里面的bIsEnabled是FieldNotify正常来说UHT要为其生成代码。但如果该类想自己手动书写这些UHT代码则可以加上CustomFieldNotify来阻止UHT生成。UWidget的cpp里因为要用别的方式UE_FIELD_NOTIFICATION_IMPLEMENT_CLASS_DESCRIPTOR因此要拒绝UHT生成。
如果自己的类也要自己UE_FIELD_NOTIFICATION_IMPLEMENT_CLASS_DESCRIPTOR则可以用上CustomFieldNotify。
## 源码例子:
```cpp
//E:\P4V\Engine\Source\Runtime\UMG\Public\FieldNotification\FieldNotificationDeclaration.h
UCLASS(Abstract, BlueprintType, Blueprintable, CustomFieldNotify)
class UMG_API UWidget : public UVisual, public INotifyFieldValueChanged
{
GENERATED_UCLASS_BODY()
public:
UE_FIELD_NOTIFICATION_DECLARE_CLASS_DESCRIPTOR_BASE_BEGIN(UMG_API)
UE_FIELD_NOTIFICATION_DECLARE_FIELD(ToolTipText)
UE_FIELD_NOTIFICATION_DECLARE_FIELD(Visibility)
UE_FIELD_NOTIFICATION_DECLARE_FIELD(bIsEnabled)
UE_FIELD_NOTIFICATION_DECLARE_ENUM_FIELD_BEGIN(ToolTipText)
UE_FIELD_NOTIFICATION_DECLARE_ENUM_FIELD(Visibility)
UE_FIELD_NOTIFICATION_DECLARE_ENUM_FIELD(bIsEnabled)
UE_FIELD_NOTIFICATION_DECLARE_ENUM_FIELD_END()
UE_FIELD_NOTIFICATION_DECLARE_CLASS_DESCRIPTOR_BASE_END();
UPROPERTY(EditAnywhere, BlueprintReadWrite, FieldNotify, Getter="GetIsEnabled", Setter="SetIsEnabled", BlueprintGetter="GetIsEnabled", BlueprintSetter="SetIsEnabled", Category="Behavior")
uint8 bIsEnabled:1;
//cpp
UE_FIELD_NOTIFICATION_IMPLEMENT_CLASS_DESCRIPTOR_ThreeFields(UWidget, ToolTipText, Visibility, bIsEnabled);
```
## 原理:
在判断条件上可见HasCustomFieldNotify的判断。
```cpp
protected static bool NeedFieldNotifyCodeGen(UhtClass classObj)
{
return
!classObj.ClassExportFlags.HasAnyFlags(UhtClassExportFlags.HasCustomFieldNotify) &&
classObj.ClassExportFlags.HasAnyFlags(UhtClassExportFlags.HasFieldNotify);
}
```